Preglow gas-discharge tube



Dec. 31, A929. J. M. SQHMIERER 9 9 PREGLOW GAS DISCHARGE TUBE Filed Nov. 10, 1924 m ll'qltase.

[FIVE/170K: Johannes Michael bchmierer Patented Dec. Ell,

:UNITEos TATEs PATENI OFFICE J'OI-IANNES MICHAEL SGI-IMIERER, OF LICH'IERFELDE, NEAR BERLIN, GERMANY, ASSIGNOR TO RADIO PATENTS CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK PREGLOW GAS-DISCHARGE TUBE Application filed November 10, 1924, Serial No. 749,038, and in Germany November 10, 1923.

This invention relates to a gas-discharging tube which is adapted to be used for amplifying, rectifying, and the production of oscillations of electric Voltages or currents and for illumination.

My invention will be understood by reference to the accompanying drawings in which:

Figure 1 illustrates diagrammatically a circuit arrangement embodying the princi ples of my invention; and Fig. 2 is a curve representing the characteristics of the circuit arrangement illustrated in Fig. 1.

My invention is based upon a form of gas discharge which essentially differs from the well known glow-discharge and occurs only at a very low intensity of current. It will be hereinafter called ante-glow-discharge as it occurs prior to the glow-discharging when the voltage on the terminals of a glowlight tube is gradually increased. The condition may be produced also by considerably reducing the strength of the electric current in a glow-light tube by considerable increase of the series resistance, It differs from the glow-discharge in the=-first instance by its luminosity which is strongest on the anode surface and grows weaker gradually towards the cathode, while with glow-discharge the cathode is covered by a luminous layer. The ante-glow discharge differs from the glowdischarge further in that striking-voltage and extinction-Voltage have the same value, while with the glow-discharge the strikingvoltage is considerably higher than the extinction-voltage. If the terminal-voltage of an ante-glow discharge tube is gradually increased the ante-glow discharge is finally transformed into a glow-discharge. If the terminal-voltage is reduced again the glow" discharge does not extinguish at once but only when it has sunk below its extinction voltage. Both forms of the gas discharge can exist together when the cathode drop of the glow-discharge is normal. The ante-glow discharge consists very. probably of a wandering of ions in one direction only, and most likely the negative ions (electrons) are wandering at accelerated speed 'to the anode. Their speed remains however too low to be capable of effecting ionization by collision, as with the glow discharge.

Figure 1 is a diagram of the circuit according to this invention. The amplifying valve V is shown in a diagrammatic manner and may be a glow discharge valve of the .well known form. It is connected in the circuit with a battery B, the secondary of the transformer T, a telephone P and a resistance B. As current is varied in the primary of the transformer t, the secondary of transformer will have alternating Voltage produced in it which is added to the voltage of the battery B and in this way affects the conducting gas of the valve V.

The valves according to this invention have, therefore, an advantage over the ordinary glow discharge valves in so far as they operate by virtue of their characteristics as is shown in Figure 2. Figure 2 shows the characteristics of an ante-glow discharge and its relation to the usual glow discharge. The current. is represented as a function of the terminal voltage. If'the terminal voltage is raised gradually then at point A the anteglow discharge begins. With a higher voltage the strength of current increases very rapidly in a linear manner. At point B the discharge suddenly changes into a glow'discharge which is represented by a considerable increase in the current. In the usual schematical diagrams this rise of current is generally represented as very small-much smaller than .it actually is.

With a further increase in voltage, the 85 current increases altho not as fast as with the ante-glow discharge. Ifv the total surface of thecathode is covered with a glow, then point D is reached and a further rise in voltage adds only little to the value of the current. If the voltage is now reduced, then the curveis obtained which coincides with the curve of the increasing voltage. However, at point C where glow discharge began, a reversal to the ante-glow d ischarge does not happen. It is possible toreduce the voltage further down to point E. If this point, as in the diagram, lies to the right of point A, then the glow discharge Will be changed into an ante-glow, discharge, when the current suddenly drops to the smaller value of point F. If, however, point E lies to the left of point A, then the glow dis charge current disappears completely. With a glow discharge the ignition voltage (point C) is higher than the extinction voltage (point E). The curve begins and ends above the abscissa. With ante-glow discharge, the ignition and extinction voltage coincide (point A). The curve begins and ends on the abscissa.

It is possible, therefore, to obtain anteglow currents as low as desired while with a glow discharge there is a lower limit of the current strength. The characteristic of the ante-glow discharge is extraordinarily steep and markedly linear, while the glow discharge curve is rather flat and strongly bent. It is for this reason that the anteglow discharge is so suitable for rectifying currents, amplifying and detecting.

The terminal voltages shown in this figure are generally reduced by a series resistance without which the usual glow discharge valves do not operatewell.

The current strength characteristic'of the ante-glow discharge intersects the axis of abscissas in contra-distinction to that of the glow discharge, which terminates earlier at a certain distance above the axis of abscissas (at decreasing load).

Ante-glow discharge tubes may be used for the-same purposes as low-discharge tubes. If they have to serve for illuminating purposes they are of the same shapes as the corresponding glow-discharge tubes, these latter being transformed into ante-glow discharge tubes by reversing of the direction of current and increasing of the series resistance. Ante-glow lamps have consequently the shape of glow-lamps, the same as letter-lamps, signal-lamps and the like, ante-glow lamps which are to be used as current direction in dicators, have electrodes or diaphragms of unequal shapes, and ante-glow rectifiers have utilized for producing oscillations only in a manner wherein they corresponded fundamentally with the arrangement of a highvacuum amplifying lamp with glow cathode. They comprised consequently a control electrode (grid). According to the invention glow-light tubes are used without grid, the

amplifying voltages or the voltages produced by the amplifying currents being simply superimposed upon the glow-discharge or antewith glow light. An amplifying effect is however produced also at feeble abnormal cathode drop, seems the apparent resistance of the tube still drops at increasing load, so that a slight increase of the voltage in the glow-discharge circuit increases the current strength considerably. The continuous current must however not cause a percelvabl saturation of the iron masses of the transformer used for superimposing the ampl fying currents upon the tube.

In order to derive in the most convenrent manner the voltage required for the working of the tube from existing mains, one ought to keep the electric distance, provided'that the same gas filling is used as in'other'commonly used glow lamps, as small as in glowlamps heretofore known, so that the tube can light at the prevailing voltage. Thls has however proved to be unfavorable.

According to my invention the electrodes are arranged at such a distance that the usual network voltages suffice not for striking but for maintaining a glow-discharge, whlch 1s initiated by means of an auxiliary discharge thatcan be caused, in a suitable manner, by

.a temporary'increase of voltage (induction impulse) or by means of an auxiliary electrode. The auxiliary electrode may be constructed, in any suitable manner, such as an external electrode. An auxiliary anode has been found to be especially reliable, the distance of which from thecathode being short enough, as in glow lamps, for it to be bridged directly by the commonly used network volt-- ages. By the insertion of a very high resistance the consumption of current by the auxiliary discharge can be reduced to such a low value that it is not necessary to cut the same out after the striking of the main charge. This arrangement can be used also at higher than the standard network voltages.

I claim 1. In an electrical system, an ionic valve including a pair of parallel cold electrodes close together, means for impressing a predeterminedvoltage across said electrodes of a value such as to maintain'the' tube in a state of pro-glow, and series means for supplying a variable voltage across said electrodes and superimposing the same upon said predetermined voltage for introducing variations in the discharge current which varia-- tion is an enlarged image of said variable voltage.

2. In an electrical circuit arrangement a termined voltage lower than the glow discharge ignition voltage across said electrodes, said circuit including a device-to be controlled and series means for superimposing upon said predetermined voltage an additional voltage for correspondingly controlling the discharge across said pair of cold electrodes for actuating said device in proportion to the variations of the'additional voltage impressed acrosssaid electrodes.

3. In an electrical control system a control circuit, a circuit arranged to be controlled by said control circuit, means interposed between said circuits comprising a gas discharge tube having a pair of cold electrodes, series means for impressing a predetermined voltage across said electrodes of such a value such as to maintain the gas discharge tube in a state of pre-glow discharge, and means for superimposing a variable voltage upon said electrodes in accordance with the operation of said control circuit for correspondingly controlling the discharge across said pairs of cold electrodes in proportion to the variations of the variable voltage impressed across said electrodes.

In testimony whereof I ailiX my signature.

JOl-IANNES MICHAEL SCHMIERER. 

